On Tue, 03 Feb 2004 05:46:52 GMT, "Plumb Bob" wrote in
Message-Id: gBGTb.214228$na.351838@attbi_s04:

"Big John" wrote in message
.. .
John

Wonder how they measured the 900 ft?

Think about it for a second... yes, mode-c.

Aircraft safely pass within 5oo' vertically of each other routinely.

I have no idea of the resolution of FAA radar, but I suppose the
testimonial evidence of the airliner crew's distance estimates could
possibly be a source for the 900' figure.